The function of a compressor is to increase pressure of curtained fluid volume into a pressure required for carrying out a refrigeration cycle. It is known to the art the so called alternative compressors, where a piston reciprocally slides within a cylinder to carry out gas compression.
In linear compressors, the piston is driven through a linear electric motor. An actuator element is coupled between the motor and the piston so that it makes the motor drives the piston to reciprocally move within the piston chamber. The piston is usually kept firmly set to the actuator element, so that the piston and the actuator element tend to move in a conjunct motion, so that an excessive vibration is undesirably caused.
In order to solve this inconvenience, the Brazilian patent application No. PI0601645-6 describes a compressor wherein the actuator element is coupled to the piston by means of an elastic element in the form of one or two resonant helical springs (indicated by number 70 in the figures of this application). Thus, the piston and the fastening elements are mounted on an end of the elastic element and the motor magnet and the fastening thereof are mounted on the other end, so that in the natural mode of compressor vibration the phase difference in phase movement between the two ends is 180°, there being a region in this elastic element where the axial vibration tends to be zero. This region in the elastic element is thus called neutral point.
According to the teachings of the patent application PI0601645-6, the coupling of the cylinder to the resonant spring must be carried out through this neutral point, so that the natural modes of compressor vibration are not changed.
In order to carry out such mounting, the compressor of document PI0601645-6 has further a position element coupling the elastic media to the cylinder. The position element (indicated by number 80 in the figures of this application) presents a rigid connection with the resonant spring, and in one of the described constructions, the element 80 is associated with a position rod flat spring affixed to the shell (vide spring number 84 in the figures of the present application).
Although the above construction represents a technical advance over the linear compressors known in the art, the configuration herein provided provides the disadvantage of being unable to present an axial rigidity sufficient for maintaining the mechanism correctly positioned when the forces acting on the set are unbalanced forces. Such unbalanced forces may cause the resulting axial force on the resonant set to be different from zero, which may cause the motor displacement, negatively influencing the efficiency of the compressor there even being the possibility of occurring impact between the same and the shell, causing several disorders.
Among the conditions that may cause such unbalancing there are the motor strength when the compressor is switched off, the gas strength during the coolant loading process and the presence of unbalanced forces that may occur during the operation of the compressor, especially those relative to the gas compression and expansion forces and the motor force.